/*
 * Copyright 2002-2018 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      https://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.http.server.reactive;

import org.eclipse.jetty.http.HttpFields;
import org.eclipse.jetty.server.HttpOutput;
import org.eclipse.jetty.server.Request;
import org.eclipse.jetty.server.Response;
import org.springframework.core.io.buffer.DataBuffer;
import org.springframework.core.io.buffer.DataBufferFactory;
import org.springframework.http.HttpHeaders;
import org.springframework.http.MediaType;
import org.springframework.util.Assert;

import javax.servlet.AsyncContext;
import javax.servlet.ServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.net.URISyntaxException;
import java.nio.ByteBuffer;
import java.nio.charset.Charset;

/**
 * {@link ServletHttpHandlerAdapter} extension that uses Jetty APIs for writing
 * to the response with {@link ByteBuffer}.
 *
 * @author Violeta Georgieva
 * @author Brian Clozel
 * @see org.springframework.web.server.adapter.AbstractReactiveWebInitializer
 * @since 5.0
 */
public class JettyHttpHandlerAdapter extends ServletHttpHandlerAdapter {

    public JettyHttpHandlerAdapter(HttpHandler httpHandler) {
        super(httpHandler);
    }


    @Override
    protected ServletServerHttpRequest createRequest(HttpServletRequest request, AsyncContext context)
            throws IOException, URISyntaxException {

        Assert.notNull(getServletPath(), "Servlet path is not initialized");
        return new JettyServerHttpRequest(request, context, getServletPath(), getDataBufferFactory(), getBufferSize());
    }

    @Override
    protected ServletServerHttpResponse createResponse(HttpServletResponse response,
                                                       AsyncContext context, ServletServerHttpRequest request) throws IOException {

        return new JettyServerHttpResponse(
                response, context, getDataBufferFactory(), getBufferSize(), request);
    }


    private static final class JettyServerHttpRequest extends ServletServerHttpRequest {

        JettyServerHttpRequest(HttpServletRequest request, AsyncContext asyncContext,
                               String servletPath, DataBufferFactory bufferFactory, int bufferSize)
                throws IOException, URISyntaxException {

            super(createHeaders(request), request, asyncContext, servletPath, bufferFactory, bufferSize);
        }

        private static HttpHeaders createHeaders(HttpServletRequest request) {
            HttpFields fields = ((Request) request).getMetaData().getFields();
            return new HttpHeaders(new JettyHeadersAdapter(fields));
        }
    }


    private static final class JettyServerHttpResponse extends ServletServerHttpResponse {

        JettyServerHttpResponse(HttpServletResponse response, AsyncContext asyncContext,
                                DataBufferFactory bufferFactory, int bufferSize, ServletServerHttpRequest request)
                throws IOException {

            super(createHeaders(response), response, asyncContext, bufferFactory, bufferSize, request);
        }

        private static HttpHeaders createHeaders(HttpServletResponse response) {
            HttpFields fields = ((Response) response).getHttpFields();
            return new HttpHeaders(new JettyHeadersAdapter(fields));
        }

        @Override
        protected void applyHeaders() {
            HttpServletResponse response = getNativeResponse();
            MediaType contentType = null;
            try {
                contentType = getHeaders().getContentType();
            }
            catch (Exception ex) {
                String rawContentType = getHeaders().getFirst(HttpHeaders.CONTENT_TYPE);
                response.setContentType(rawContentType);
            }
            if (response.getContentType() == null && contentType != null) {
                response.setContentType(contentType.toString());
            }
            Charset charset = (contentType != null ? contentType.getCharset() : null);
            if (response.getCharacterEncoding() == null && charset != null) {
                response.setCharacterEncoding(charset.name());
            }
            long contentLength = getHeaders().getContentLength();
            if (contentLength != -1) {
                response.setContentLengthLong(contentLength);
            }
        }

        @Override
        protected int writeToOutputStream(DataBuffer dataBuffer) throws IOException {
            ByteBuffer input = dataBuffer.asByteBuffer();
            int len = input.remaining();
            ServletResponse response = getNativeResponse();
            ((HttpOutput) response.getOutputStream()).write(input);
            return len;
        }
    }

}
